New Clues Into Ebola as Ill Nurse Improves

A Scottish nurse who survived Ebola only to fall critically ill some nine months later with meningitis is beginning to recover, doctors said Wednesday.

“She’s made significant progress in the past few days,” said Dr. Daniel Bausch, a technical consultant with the World Health Organization who has visited the Royal Free Hospital in London, which is treating the nurse, Pauline Cafferkey. Dr. Bausch added that Ms. Cafferkey had improved so much that she was even using an iPad.

Equally important, experts say, is what Ms. Cafferkey’s infection is telling them about virus, and the implications for other survivors in West Africa.

Dr. Bausch said that her blood and spinal fluid had tested positive for traces of the virus earlier this month. Her blood was negative after it was recently retested.

She has been treated with an experimental antiviral compound that is thought to work by incorporating itself into the genetic material while the Ebola virus is being copied, stopping a new virus from forming. While it is unknown whether the compound helped Ms. Cafferkey recover, it was shown to protect 12 primates against a lethal Ebola virus infection, said Travis Warren, principal investigator at the United States Army Medical Research Institute of Infectious Disease in Fort Dietrich, Md.

Ms. Cafferkey’s doctor had seen a presentation about the compound, GS5734, at a recent conference. “When he came back to the U.K., he immediately contacted us and said he was requesting compassionate use of the drug,” said Norbert Bischofberger, chief scientific officer at Gilead Sciences in California, which produced the compound and safety tested it in humans.

Scientists are compiling what they have observed in animals and are finding that perhaps they should not have been surprised by her illness. In one case, macaques infected with Ebola began to recover, but two to three weeks after infection, “they’d start to deteriorate,” said Thomas W. Geisbert a professor of microbiology and immunology at the University of Texas Medical Branch at Galveston.

The monkeys showed signs of neurological disease. Evidence of the virus was found in their brains and other organs not typically infected by Ebola, said Lisa Hensley, a scientist with the National Institutes of Health. Because the phenomenon was so rare, and the number of animals affected so small, other scientists who have seen similar results were not sure what to make of it.

One question is why the virus persisted so long in Ms. Cafferkey, who became infected in Sierra Leone, where she had gone as a volunteer, and what it was doing in that time. Clues may come from studies of Ebola in nature. Ebola is thought to persist in bats without causing disease.

It may be that in certain immunologically protected parts of the human body, including the central nervous system, it may be replicating at a very low level. Scientists have found no evidence that Ebola is capable of going dormant in human cells and then reactivating.

At a meeting on Wednesday at Fort Dietrich, experts discussed whether Ms. Cafferkey’s second illness could have been caused by the virus beginning to replicate more intensely again or by the immune system finally gaining access to the last pocket of virus.

In health surveys, survivors of Ebola and a similar virus, Marburg, have reported neurological symptoms and other complaints.

“We’ve never quite been sure if it was related to the Ebola virus” or other illnesses, said John M. Dye Jr., chief of viral immunology with the Army Medical Research Institute. Dr. Dye and other researchers stressed, however, that grave complications were likely to be rare, and that they might be a byproduct of the severe initial infection Ms. Cafferkey had, which she may have survived only because she had a higher level of care in London.

“We don’t want this to be used to enhance the stigma that people suffer,” Dr. Bausch said. Still, doctors will now need to test any Ebola survivor who shows signs of meningitis, he said.

Experts praised Ms. Cafferkey and other survivors who have shared their clinical details. “We’re going to learn so much from her,” Dr. Dye said.

A version of this article appears in print on , Section A, Page 4 of the New York edition with the headline: New Clues Into Ebola as Ill Nurse Improves. Order Reprints | Today’s Paper | Subscribe